1. Field of Invention
The present invention relates generally to the field of optimizing the operation of a content delivery network. More particularly, the present invention is in one exemplary aspect related to apparatus and methods for providing adaptive network routing.
2. Description of Related Technology
Recent advances in digital information processing and technology have made a whole range of services and functions available for delivery to consumers at various types of devices for reasonable prices and/or subscription fees. These services and functions include digital content or programming (movies, advertisements, etc.), digital video-on-demand (VOD), personal video recorder (PVR) and networked PVR (nPVR), Internet Protocol television (IPTV), digital media playback and recording, as well high speed Internet access (including so-called “Internet TV”, where television programming is delivered over the Internet without QoS) and IP-based telephony (e.g., VoIP).
Currently, many of these services are provided to the user via a wide variety of different equipment environments and delivery paradigms (including, inter alia, cable or satellite modems via QAMs, Hybrid Fiber-copper (HFCu) distribution via indigenous POST/PSTN wiring in a premises, Wi-Fi™ or WiMAX hubs, Ethernet hubs, gateways, switches, and routers), to a plurality of user equipment types. For example, content may be delivered to users at set-top boxes, personal (desktop) computers, laptop computers, other mini-computers (such as so-called “netbooks”, mini-notebook computers), 3G or 4G smartphones, and/or other devices.
Traditional cable network delivery services are optimized for broadcasting a limited number of services to a much larger audience of consumers. Cable networks compete with other systems, such as satellite broadcast and HFCu service. Within cable networks, so-called “narrowcast” content is provided for a relatively small number of targeted consumers. In a broad sense, narrowcast content is content (or its associated bandwidth) that is more narrowly distributed to a subset of the subscriber pool serviced by a given network. Examples of narrowcast content include VOD, “startover” functionality, DOCSIS, and switched digital video delivery. Narrowcast applications (such as advertising, data, premium content, etc.) generally have greater value for the consumer, and are a source of significant revenue for network providers. Additionally, narrowcast applications have traditionally been one key differentiation between cable network providers and their competitors (e.g., satellite service).
However, while narrowcast content has significant business value, the technical realization of narrowcast content insertion (including so-called “targeted” content, such as targeted advertising or promotions) greatly complicates cable network topologies and operation.
Originally, cable networks were carefully planned around relatively static parameters; for example, analog delivery of channels operated using fixed frequencies and time slots. As cable networks have transitioned to digital content and narrowcast services (such as Switched Digital Video (SDV) and Video-On-Demand (VOD)), additional infrastructure has been added to support splicing, mixing, etc. within the existing analog delivery framework. Current cable networks are often a less-than-coherent mix of somewhat haphazardly organized equipment. Worse still, a growing maze of wiring and cabling connects clusters of specialized hardware which further exacerbates network management challenges. Typical cable network infrastructure is often both hard to maintain and modify, and increasingly difficult to upgrade. As narrowcast services continue to diversify and drive increasing portions of business revenue, the demands on network infrastructure may rapidly exceed sustainable limits.
FIG. 1 illustrates one such prior art content delivery network configuration. The various components of the network 100 include (i) one or more data and application origination points 102; (ii) one or more content sources 103, (iii) one or more application distribution servers 104; (iv) one or more VOD servers 105, and (v) customer premises equipment (CPE) 106. The distribution server(s) 104, VOD servers 105 and CPE(s) 106 are connected via a bearer (e.g., HFC) network 101. A simple architecture comprising one of each of the aforementioned components 102, 104, 105, 106 is shown in FIG. 1 for simplicity.
FIG. 1a illustrates one typical prior art headend architecture. The headend architecture 150 comprises typical headend components and services including billing module 152, subscriber management system (SMS) and CPE configuration management module 154, cable-modem termination system (CMTS) and OOB system 156, as well as LAN(s) 158, 160 placing the various components in data communication with one another.
The architecture 150 of FIG. 1a further includes a multiplexer/encrypter/modulator (MEM) 162 coupled to the HFC network 101 adapted to “condition” content for transmission over the network. The distribution servers 104 are coupled to the LAN 160, which provides access to the MEM 162 and network 101 via one or more file servers 170. The VOD servers 105 are coupled to the LAN 160 as well, although other architectures may be employed (such as for example where the VOD servers are associated with a core switching device such as a Gigabit Ethernet device). As previously described, information is carried across multiple channels. Thus, the headend must be adapted to acquire the information for the carried channels from various sources. Typically, the channels being delivered from the headend 150 to the CPE 106 (“downstream”) are multiplexed together in the headend and sent to neighborhood hubs via a variety of interposed network components.
As shown in FIG. 1b, the network 101 of FIGS. 1 and 1a comprises a fiber/coax arrangement wherein the output of the MEM 162 of FIG. 1a is transferred to the optical domain (such as via an optical transceiver 177 at the headend or further downstream). The optical domain signals are then distributed to a fiber node 178, which further distributes the signals over a distribution network 180 to a plurality of local servicing nodes 182. This provides an effective 1:N expansion of the network at the local service end. Each local service node 182 provides appropriate content to a “service group” of CPEs 106.
Content (e.g., audio, video, data, files, etc.) is provided in each downstream (in-band) channel associated with the relevant service group. To communicate with the headend or intermediary node (e.g., hub server), the CPE 106 may use the out-of-band (OOB) or DOCSIS channels and associated protocols. The OCAP 1.0, 2.0, 3.0 (and subsequent) specification provides for exemplary networking protocols both downstream and upstream.
FIG. 1c illustrates an exemplary prior art “switched” network architecture (e.g., “switched digital video”). Switching architectures allow improved efficiency of bandwidth use for ordinary digital broadcast programs. Ideally, the subscriber is unaware of any difference between programs delivered using a switched network and ordinary streaming broadcast delivery. FIG. 1c shows the implementation details of one exemplary implementation of this broadcast switched network architecture. Specifically, the headend 150 contains switched broadcast control and media path functions 190, 192; these element cooperating to control and feed, respectively, downstream or edge switching devices 194 at the hub site which are used to selectively switch broadcast streams to various service groups. A BSA server 196 is also disposed at the hub site, and implements functions related to switching and bandwidth conservation (in conjunction with a management entity 198 disposed at the headend). An optical transport ring 197 is utilized to distribute the dense wave-division multiplexed (DWDM) optical signals to each hub.
In addition to “broadcast” content (e.g., video programming), the systems of FIGS. 1a and 1c also deliver Internet data services using the Internet protocol (IP).
Referring again to FIG. 1c, the IP packets associated with Internet services are received by edge switch 194, and forwarded to the cable modem termination system (CMTS) 199. The CMTS examines the packets, and forwards packets intended for the local network to the edge switch 194. Other packets are discarded or routed to another component.
The edge switch 194 forwards the packets received from the CMTS 199 to the QAM modulator 189, which transmits the packets on one or more physical (QAM-modulated RF) channels to the CPE. The IP packets are typically transmitted on RF channels that are different that the RF channels used for the broadcast video and audio programming (e.g., DOCSIS QAMs). The CPE 106 are each configured to monitor the particular assigned RF channel (such as via a port or socket ID/address, or other such mechanism) for IP packets intended for the subscriber premises/address that they serve.
Currently, typical “digital” cable networks such as those described with respect to FIGS. 1-1c above employ video signals in the TDM (Time Division Multiplexing) domain that are transformed to FDM (Frequency Division Multiplexing) domain for delivery within the HFC plant. However, this approach is implemented in a largely discrete fashion; the fundamental technologies perform single channel conversion or block up-conversion of multiple adjacent channels in varying blocks of channels (e.g., 2, 4, 8, 16, or 32). The most advanced technologies employed to date perform comb-channel insertion, wherein single channels or blocks of channels are inserted anywhere within the RF spectrum. This insertion or signal combining is effectively performed in an analog “wired” domain, which unfortunately does not lend itself to ready reconfiguration without physical rewiring.
For example, in terms of hardware, a typical prior art cable network hubsite (see FIG. 1c) has significant requirements in terms of space, power, and cooling due to the many components needed to (i) effect the aforementioned signal combining/insertion functions; and (ii) distribute the combined signal to individual service groups and subscribers. A typical prior art hubsite rack has 42 Rack Units (RU), and consumes roughly 1 Amp of electrical current per RU (2 Amps if there is redundancy). A hubsite supporting 80 service groups may consume 20 full racks to generate the necessary spectrums. Moreover, there typically are literally thousands of wires, specifically coaxial cables, within a typical hubsite. Such complexities are also prone to equipment failure (more components and cables generally equates to a higher chance of failure), and service wiring mistakes.
Hybrid Fiber Copper (HFCu) systems such as the U-verse® service offered by AT&T suffer many similar disabilities, largely due to the fact that the indigenous transport for much of the provided service (i.e., copper wiring within a user's premises and beyond, that was originally installed for providing POTS or PSTN telephony service only) is not optimized for narrowcast content delivery.
Another issue with extant content delivery systems relates to so-called “service velocity”; defined as the rate with which new services can be employed or adopted within a cable or other network. Simply stated, the more difficult such implementation is (due to e.g., having to rewire or reconfigure portions of a network), the lower the velocity. Service velocity is an essential differentiating factor in terms of the subscriber; as time goes on, subscribers want more and better services faster, especially those that are individualized to their particular needs or situation. Hence, such subscriber-specific service velocity must be considered in solutions going forward, and extant delivery systems such as HFC cable topologies cannot be considered optimized for this factor. Currently, to implement new services, changes to the network topology and significant amounts of labor (e.g., “truck rolls”) are required, due largely to a lack of remote reconfiguration capability, and what amounts to a largely “circuit switched” topology.
Similarly, to establish or discontinue services for new or existing subscribers, being so labor-intensive, results in MSOs being reluctant to make these changes without a significant opportunity for economic recovery (e.g., a commitment from the subscriber for a sufficiently long period of time, or a higher rate). Stated differently, if the existing delivery network could be reconfigured with little or no labor, then the threshold for establishing/terminating service to a given subscriber could feasibly be lowered (practically corresponding to lower service costs, and/or shorter service commitments), which would ostensibly entice more subscribers to sign up for service, since the cost (risk)-benefit equation tilts further in their favor. This would allow network operators such as MSOs to more effectively leverage some of their salient advantages or attributes; i.e., customer service, individualization of service, reliability, etc.; as more people try the MSO's service (due to reduced entry threshold), the more people will conceivably be convinced to continue service with the MSO, thereby increasing the MSO's subscriber base. Conversely, as the subscriber's service cost and length of commitment increase, they will be less likely to sign up or stay with the MSO.
Moreover, current content distribution network infrastructures are poorly suited for prototyping new technologies. Current prototyping is expensive for the network (e.g., significant labor and capital outlays which may or may not be profitable), and can disrupt consumer services (e.g., as equipment is wired, “juggled”). Faster prototyping capabilities will benefit both network operators and users/consumers.
Accordingly, there is a salient need for improved apparatus and methods for efficiently distributing content (including the aforementioned narrowcast services) within a digital network. Such improved apparatus and services should simplify infrastructures for existing digital services, and support other requisite services such as analog, while also flexibly accommodating future changes to content delivery mechanisms and services. Rapid and remote reconfigurability would also be a highly desirable feature, thereby obviating much labor associated with rewiring of traditional networks to add new services.